doc: update release notes for bnxt
doc: update release notes for bnxt

Update release doc briefly describing updates to bnxt PMD.

Signed-off-by: Ajit Khaparde <01965fbd61169dc18f3fb5e13de7f67d298f8924@broadcom.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk